With development of product manufacturing technologies, various devices are applied to user lives. For example, a user uses a portable device to listen to music or watch a video. To improve user experience, some device parameters can be adjusted by the user. Usually, adjustable parameters such as a device volume and a progress bar of a player installed on a device can be set by the user.
However, when adjusting adjustable device parameters, the user finds that most devices cannot accurately locate an adjustable parameter adjustment. For example, a device usually uses a capacitive touchscreen, and the capacitive touchscreen operates by means of human-body current induction. An operating principle of the capacitive touchscreen is as follows. A coupling capacitor forms between a user finger and a touchscreen surface because of a human-body electric field when the user finger touches the capacitive touchscreen. Because a high frequency signal is connected to the touchscreen, the finger absorbs a very small current. The current flows from each of electrodes on four corners of the touchscreen, and in theory, currents flowing from the four electrodes are proportional to distances between the finger and the four corners. The device obtains a location of a touch point of the user finger by calculating proportions of the four currents. As a result, information such as a moving distance of the user finger may also be learned of. However, capacitance changes with a contact area between the user finger and the touchscreen surface. In a possible case, when the user finger moves an extremely small distance to perform an extremely small adjustment on the adjustable parameter, a force application direction of the user finger also changes. A contact region between the user finger and the touchscreen before the movement basically matches a contact region between the user finger and the touchscreen after the movement. Therefore, the device considers that the user does not move the finger, and the device does not adjust the adjustable parameter. In another possible case, when the user adjusts the adjustable parameter to a value expected by the user, a shape of the touchscreen unevenly changes in a process in which the user finger moves away from the touchscreen. As a result, the device considers that the user is continuously moving the finger, and the device continuously adjusts the adjustable parameter. Consequently, in the other approaches, a device cannot accurately lock a location at which a user finger touches a touchscreen and cannot accurately adjust an adjustable parameter according to a user requirement.